A planar illumination light source device according to Patent Document 1 includes at least one primary light source and a plate-shaped light guiding body that guides the light emitted from the primary light source and that has a light-incident-end face on which the light emitted from the primary light source is incident and a light emission plane for emitting light to be guided; the light guiding body has a light emission mechanism on at least one of the light emission faces and the back face thereof, and also has at least one local lens array formation part on at least one of the light emission faces and the back face thereof, each of the local lens array formation parts has at least one local lens array, and the local lens array is formed in a direction different from the direction of a peak light intensity within a brightness distribution at an incident position of a highest light intensity of light emitted from the primary light source, the direction further being incident on the light incident end face. Thereby the inconsistency in brightness is solved.
An illumination display device according to Patent Document 2 includes a lamp housing having an opening on one end and having a light source device accommodation portion whose inner wall is a light reflection plane, a light emitting diode that is a light source for illumination provided on a bottom wall of the light source accommodation portion, and a display plate having a transmissive plate that is provided to cover the opening in order to display a desired display, and a light guiding body being fit between the light emitting diode and the display plate in the light source accommodation portion in order to form a contact plane together with the inner wall of the light source accommodation portion and in order to make incident light scatter and to make it a planar illumination light in which the texturing process is performed on the inner wall surface. Thereby, the light of a light source having a high directionality such as that of an LED is uniformized in order to increase the visibility of the display.
In other words, in the technique of Patent Document 2, light emitted from a light emitting diode is diffused and reflected by using an inner wall that has received the texturing process, and is uniformized by using the operation of a diffusion film or the like.
Also, in Patent Document 3, it is disclosed that reflection is repeated between the light reflected from a micro reflection part in a diffusion layer formed on a reflection plane of light and a reflector provided in the vicinity of a light emitting diode (LED), thereby uniformized light is obtained.
Also, in Patent Document 4, it is disclosed that directional light emitted from an LED (especially intensive light directly above the LED) is reflected in the direction of the LED by using a reflection part formed on a radiation plane. Thereby, the direction of the light is changed, and the intensity of the light from the LED is reduced in order to obtain uniformized light.    Patent Document 1:    Japanese Patent Application Publication No. 2002-343124    Patent Document 2:    Japanese Patent Application Publication No. 2003-186427    Patent Document 3:    Japanese Patent Application Publication No. 2005-284283    Patent Document 4:    Japanese Patent Application Publication No. 2006-12818